1. Field of the Invention
This invention relates to an artificial island for installing oil drilling equipment in ice covered sea areas, which is particularly suitable for installing such equipment in a comparatively shallow ice covered sea area of not more than twenty meters in depth.
2. Description of the Prior Art
In an ice covered sea area, such as the Arctic Ocean, the depth of water is comparatively small or not more than 20 m, and the fast ice in such a sea area is said to be moved approximately 20 m at most during the winter months.
When an oil drilling operation is conducted in such an ice covered sea area, great quantities of sand and gravel are accumulated to form an artificial island on which oil drilling equipment is then installed, or oil drilling equipment is installed directly on the fast ice without forming such an artificial island.
However, it is necessary that the area of an artificial island to be formed in an ice-covered sea area for oil drilling operation be considerably large since the artificial island has to be capable of withstanding floating ice or a high ice pressure. It takes a long period of time and great cost to build an artificial island of a large area. Moreover, it is very difficult to remove such an artificial island after an oil drilling operation has been completed. It therefore costs a great deal to remove an artificial island built in such a sea area. In addition, removing an artificial island causes environmental pollution.
Setting an oil drilling installation directly on the fast ice is limited to one or two months in the depth of winter, in which the fast ice is not moved to a large degree. Moreover, drill breakage is possible during an oil drilling operation due to the movement of the ice.